• 한국융합학회논문지
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• 제11권11호
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• pp.249-255
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• 2020

본 연구에서는 프레스 시험 중 시편에서 발생하는 음향방출 신호와 신호필터링을 통해 시편의 건전성을 평가하는 연구를 진행하였으며, 실험결과를 통해 음향방출 진동횟수와 최대진폭 두 개의 음향방출 파라미터를 프레스 시편 건전성 판단에 적용하고자 한다. 프레스 장치를 이용한 구멍확장시험 중에는 시편에서 탄성파가 발생하며, 탄성파를 음향방출 센서를 통해 수집하였다. 이 신호를 바탕으로 음향방출 파라미터를 획득한 뒤, 시편의 크랙을 감지하는 연구를 진행하였다. 명확한 건전성 판단을 위해 STFT(Short Time Fourier Transform)와 고주파수 통과 필터(High-Pass Filter)를 이용하였다. 향후 본 연구에서 제안하는 신호 처리 기법 및 해당 파라미터를 활용한다면 프레스공정에서의 시편 건전성 평가 성능을 향상시킬 수 있을 것이라 생각된다.

• Journal of the Korean Wood Science and Technology
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• 제45권1호
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• pp.85-95
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• 2017

본 연구는 연륜연대학적 방법을 이용하여 노거수 수령의 정확한 추정을 위해 수행되었다. 연구지역은 충청북도 괴산군(CBGS), 전라남도 구례군(JNGR), 경상북도 울진군(GBUJ)이며, 수종은 각 지역의 보호수로 지정된 느티나무와 소나무로 하였다. CBGS, JNGR, GBUJ에서 채취한 느티나무는 각각 12, 8, 6본이며, 소나무는 각각 10, 3, 9본이다. 시료(생장편)는 생장추(직경 5.2 mm)를 이용하여 채취하였다. 정확한 연륜측정을 위해 느티나무는 활주식 마이크로톰으로 횡단면을 절삭하였으며, 소나무는 사포를 이용하여 횡단면을 연마하였다. 연륜폭은 이용하여 0.01 mm 정확도로 측정하였다. 느티나무의 경우 CBGS와 GBUJ에서 203 (1813~2015)년의 연륜연대기가 작성되었으며, JNGR에서는 175 (1841~2015)년의 연륜연대기가 성공적으로 작성되었다. 소나무의 경우 CBGS, JNGR, GBUJ에서 각각 154(1862~2015)년, 175 (1841~2015)년, 250 (1776~2015)년의 연륜연대기가 성공적으로 작성되었다. 느티나무와 소나무의 지역별 대표연륜연대기를 상호 비교한 결과 대부분 낮은 t 값과 Glk 값을 보여 대표연륜연대기 상호간 일치도가 낮은 것으로 확인되었다. 최근 50년 평균 기온과 강수량 분포도를 지역별 대표연륜연대기와 비교한 결과, 지역별 대표 연륜연대기 패턴은 온도보다 강수량에 의해 결정되는 것이 확인되었다. 따라서 향후 연륜연대학적 방법을 이용한 정확한 수령추정을 위해선 강수량이 고려된 지역별 대표연륜연대기가 준비되어야 할 것이다.

• Archives of Plastic Surgery
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• 제39권4호
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• pp.397-403
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• 2012

Background Nonabsorbable sutures are favorable for repairing flexor tendons. However, absorbable sutures have performed favorably in an animal model. Methods Two-strand sutures using the interlocking modified Kessler method with polydioxanone absorbable sutures 4-0 were used to repair completely ruptured flexor tendons in 55 fingers from 41 consecutive patients. The medical records of average 42 follow up weeks were analyzed retrospectively. The data analyzed using the chi-squared test, and Fisher's exact test was used for postoperative complications. The results were compared with those of other studies. Results Among the index, middle, ring, and little fingers were injured in 9, 17, 16, and 13 fingers, respectively. The injury levels varied from zone 1 to 5. Of the 55 digits in our study, there were 26 (47%) isolated flexor digitorum profundus (FDP) injuries and 29 (53%) combined FDP and with flexor digitorum superficialis injuries. Pulley repair was also conducted. Concomitant injuries of blood vessels and nerves were found in 17 patients (23 fingers); nerve injuries occurred in 5 patients (10 fingers). Two patients had ruptures (3.6%), and one patient had two adhesions (3.6%). Using the original Strickland criteria, all the patients were assessed to be excellent or good. Also, fibrosis and long-term foreign body tissue reactions such as stitch granuloma were less likely occurred in our study. Compared to the Cullen's report that used nonabsorbable sutures, there was no significant difference in the rupture or adhesion rates. Conclusions Therefore, this study suggests that appropriate absorbable core sutures can be used safely for flexor tendon repairs.

• 한국안전학회지
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• 제10권4호
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• pp.68-74
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• 1995

This paper analyzes the behaviors of the membrane under drop impact loadings using the acoustic emission technique. The analysis is useful for evaluating the strength of the membrane as well as for studying its damping characterisics due to the corrugation and the ring knot. The membrane for LNG storage tank is basically composed linear and circular elements. Two membrane specimens have approximately same drop impact mass and same drop speed. Locan 320 system with piezoelectric sensor is used in the experimental measurement. Experimental results for the membranes indicated that AE siganls having higher energies were generated with increasing drop impact loadings. It was confirmed that the ring knot. membrane has high absorption of drop impact loadings in comparison with the flat membrane. These results are very important to reliable design and to improve the safey of the membrane components.

• 한국가구학회지
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• 제25권4호
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• pp.258-267
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• 2014

We present the dendrochronological dates of Korean wooden furnitures in National Museum of Korea. Six of fourteen were successfully dated. Rice Chest (구 2225) was dated A.D. 1805 +. Others dated were Rice Chest (신수 9479; A.D. 1819), Rice Chest (신수 9475; A.D. $1826{\pm}10$), Ganghwa-Chest with a flap door (구 2341; A.D. $1842{\pm}10$), Ganghwa-Chest with a flap door (구 3124; A.D. $1859{\pm}10$), Chest with a flap door (신수 15731; A.D. $1865{\pm}10$). Most of existing cabinets were made in 1800s. Rice Chest (신수 9479) was the earliest piece of furniture in the collections of National Museum. The furniture is usually composed one species. The major species was Pinus densiflora.

• Journal of Forest and Environmental Science
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• 제30권1호
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• pp.56-61
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• 2014

Macroscopic and microscopic characteristics of Yellow-hearted pine and Red pine were investigated. Wood color, annual ring width and latewood percentage were observed by the naked eye. Anatomical properties as the structure of three sections and cell dimensions were examined by an optical microscopy. As a result, the color of bark in Yellow-hearted pine was Reddish-grey, and Red pine showed brown or gray. The color of heartwood and sapwood in Yellow-hearted pine was deep-yellow to brown and creamy-white. And the color of heartwood and sapwood in Red pine was light-brown and light-yellow. The annual ring width of Yellow-hearted pine was narrower than that of Red pine, and the latewood percentage of Yellow-hearted pine was a little higher than that of Red pine. There was no significant difference in the anatomical characteristics between Yellow-hearted pine and Red pine.

• 대한수학회보
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• 제40권2호
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• pp.223-234
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• 2003

This note contains the following results for a ring A : (1) A is simple Artinian if and only if A is a prime right YJ-injective, right and left V-ring with a maximal right annihilator ; (2) if A is a left quasi-duo ring with Jacobson radical J such that $_{A}$A/J is p-injective, then the ring A/J is strongly regular ; (3) A is von Neumann regular with non-zero socle if and only if A is a left p.p.ring containing a finitely generated p-injective maximal left ideal satisfying the following condition : if e is an idempotent in A, then eA is a minimal right ideal if and only if Ae is a minimal left ideal ; (4) If A is left non-singular, left YJ-injective such that each maximal left ideal of A is either injective or a two-sided ideal of A, then A is either left self-injective regular or strongly regular : (5) A is left continuous regular if and only if A is right p-injective such that for every cyclic left A-module M, $_{A}$M/Z(M) is projective. ((5) remains valid if 《continuous》 is replaced by 《self-injective》 and 《cyclic》 is replaced by 《finitely generated》. Finally, we have the following two equivalent properties for A to be von Neumann regula. : (a) A is left non-singular such that every finitely generated left ideal is the left annihilator of an element of A and every principal right ideal of A is the right annihilator of an element of A ; (b) Change 《left non-singular》 into 《right non-singular》in (a).(a).

• 대한수학회보
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• 제38권1호
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• pp.137-142
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• 2001

In this paper, we initiate the study of some annihilator conditions on polynomials which were used by Kaplansky [4] to abstract algebras of bounded linear operators on a Hilbert spaces with Baer condition. On the other hand, p.p. rings were introduced by A. Hattori [3] to study the torsion theory. The purpose of this paper is to introduce near-rings with Baer condition and near-rings with p.p. condition which are somewhat different from the ring case, and to extend a results of Armendarz [1] to polynomial near-rings with Baer condition in somewhat different way of Birkenmeier and Huang [2].

• 대한화학회지
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• 제52권4호
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• pp.356-361
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• 2008

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.356.1-356.1
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• 2002

The carbocyclic nucleosides have extensively studied as a promising antiviral agents having chemical and metabolical stability. In our research program for discovery of antiviral drugs. some novel dimethylcyclopropyl nucleosides possessing additional methyl spacer between purine bases and the ring was synthesized. The important intermediate, dimethylcyclopropyl alcohol was synthesized from ethyl chrysanthemate via its ozonolysis, isomerization reduction. (omitted)